Books like Captain Underpants and the Big, Bad Battle of the Bionic Booger Boy, Part 1: The Night of the Nasty Nostril Nuggets

The sixth "epic novel" in Dav Pilkey's hugely popular series explains the awful truth about Captain Underpants (he is really the school principal), details "the night of the nasty nostril nuggets," offers up "the unnecessarily disgusting chapter," and even explains how "you can't have your cape and Edith, too." George and Harold are "C" students (and bad spellers), but they are very good at "saving the entire planet from the nasty forces of unrelenting evil" and also at ketchup-toilet pranks. Unfortunately, they can't save Melvin Sneedly from getting paddled by his bionic hamster. But, frankly, they wouldn't want to, because besides being the school brainiac, Melvin is also a tattletale. When his robot-making hobby backfires horribly, Melvin transforms himself into the Bionic Booger Boy instead of a bionic superboy. Can Captain Underpants save everyone from this "greenish, glistening behemoth?"